High reliability robotic cross-connect systems

ABSTRACT

An apparatus includes a plurality of connector track elements, each extending substantially perpendicularly from a coupling plane, wherein a particular connector track element of the plurality of connector track elements includes a distribution of at least two magnets adjacent unattached end thereof, a polarity of the magnets on the particular connector track element being selected to provide magnetic repulsion as to at least one adjacent connector track element.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/949,861, filed Nov. 23, 2015, which claims priority from U.S.Provisional patent application number 62/091,541, filed Dec. 14, 2014,the entire contents of both of which are hereby fully incorporatedherein by reference for all purposes.

BACKGROUND 1. Field of the Invention

The present invention is directed in general to large scale roboticcross-connect systems providing low loss, software-defined fiber opticconnections between a large number of pairs of ports. Mechanisms in thesystems incorporate numerous features that ensure reliable operation.

2. Description of the Background Art

Large scale automated fiber optic cross-connect switches andsoftware-defined patch-panels enable data centers and data networks tobe fully automated, wherein the physical network topologies aresoftware-defined or programmable, for improved efficiencies and costsavings. Current fiber optic switch technologies such as cross-barswitches scale as N² (N is the number of ports) making them ill-suitedfor large scale production networks. Prior art disclosures of cross-barswitches include U.S. Pat. No. 4,955,686 to Buhrer et al, U.S. Pat. No.5,050,955 to Sjolinder, U.S. Pat. No. 6,859,575 to Aral et al, and U.S.Patent No. 2011/0116739A1 to Safrani et al.

More recent automated patch-panel approaches that scale as linearly withthe number of ports utilize braided fiber optic strands. Advances in themathematics of topology and Knot and Braid Theory (U.S. Pat. Nos.8,068,715, 8,463,091, 8,488,938 and 8,805,155 to Kewitsch) have solvedthe fiber entanglement challenge for dense collections of interconnectstrands undergoing arbitrary and unlimited reconfigurations. Since thisKnots, Braids and Strands (KBS) technology scales linearly in the numberof interconnect strands, significant benefits over cross-bar switchessuch as density and hardware simplicity are realized. Existing systemsfeaturing autonomous patch panel systems and implementing KBS algorithmsin accordance with the Kewitsch patents referenced above typicallyutilize a pick and place robotic actuation system with a gripper at theend of the robotic arm to grab and transport a fiber optic connector andthe fiber optic strand extending therefrom to a central backbone in thesystem. The robotic arm is of a narrow width and extended depth to allowit to descend into the dense fiber optic interconnect volume with nomechanical interference and no contact with surrounding fibers, yetstill having sufficient rigidity to experience minimal deflection undertransverse forces including magnetic repulsion and tension originatingfrom the fiber being carried in the gripper therein. However, furtherimprovements in this new class of physical fiber optic switching orconnection management system are always desirable, including thoserelating to improvements in compactness, hardware simplicity andoperative reliability, singly or in combination.

SUMMARY

The present invention relates to apparatus to improve the performance ofthis new type of cross-connect utilizing braided fiber optic strands andthe application of the mathematics of topology to this scalingchallenge. In this invention, a highly reliable automated cross-connectsystem is employed with multiple unique hardware and operative featuresto provide superior compactness, performance and reliability. Forexample, a dense three-dimensional matrix of parallel and preciselyseparated connector elements is distributed through two orthogonaldimensions, with a plurality of multi-functional elements being disposedalong each connection path in the third dimension. The connector pathseach comprise individual ones of a plurality of linear base elementswhich are each separately movable to align with a chosen base element inthe cross-connect system. The invention includes unique magneticallylatched fiber optic connector devices which enable the system to providemultiple different user defined states of insertion loss. The devicesinclude reliable, self-guiding, attraction mode magnetic latching tofacilitate repeatable robotic engagement and reconfiguration. Roboticminiature gripper devices that retain the magnetically latched fiberoptic connectors are further disclosed, wherein the miniature gripperincludes integral sensing and actuation means to ensure properengagement with a selected connector. Furthermore, the system isconfigured with movable rows of multiple, spaced apart horizontalconnector receptacles, stacked vertically therein. Each row is comprisedof multiple parallel connector tracks, and each connector track includesa mating connector receptacle, a fiber optic interface port, andcombined mechanical and magnetic reference features which are configuredto achieve reliable latching and locating of both the fiber opticconnector device and the gripper device. The movable rows of connectorreceptacles incorporate precision injection molded translationassemblies and actuation means to accurately and precisely translaterows between one of three horizontal locations. These locations generatethe vertical row shuffling response as dictated by the KBS algorithm andaid in improving the volumetric efficiency of the system.

The gripper consists of a two-part body, a central body whichmechanically engages or interlocks with a particular target connectorextended member in between the multiplicity of surrounding extendedmembers, and a driven, translatable outer body or frame incorporatingmeans to engage and sense the reconfigurable internal fiber opticconnector assembly. The narrow width gripper, attached to the lower endof the controlled telescopic arm, descends down onto a selected centeredconnector row until a gripper interlock sensor detects proper engagementwith the extended member. The gripper outer body translates parallel tothe extended member to plug-in, unplug or partially disconnect theinternal connector assembly. The translation mechanism uniquelyincorporates a drive line, wrapped around a motor drive shaft with asmall but precise excess length to control bidirectional lateraltranslation of the gripper. This obviates the stalling of the drivemotor upon a startup acceleration from a state of rest.

The cross-connect system is also based on a three-dimensional array ofparallel but precisely laterally separated elongated reference membersdisposed in an augmentable vertical stack of horizontal rows. Thereference members are narrow and of selected uniform length havingchosen flexure properties, and include sets of small permanent magnetsdeployed so as to utilize both magnetic attraction and repulsion forcesduring different and separate operative states of engagement. Eachnarrow reference member is positioned to be closely adjacent to adifferent receiving aperture into which the end of a different opticalfiber connector can be inserted. The end apertures lie in transverselydisposed horizontal rows in a vertical connection plane and each ispositioned to potentially receive the end of the optical fiber connectorrepositioned by the system. The small permanent magnets along theirlengths are positioned selectively and with such polarities as toprovide at least two stable insertion positions and also a transverselyrepulsive force, to maintain adjacent elements separate in a densethree-dimensional array of elements.

This application further discloses a uniquely compact configuration foraccessing and repositioning optical fibers on command Telescopic roboticarm devices of minimal transverse compliance and high length efficiency(ratio of the range L₂ to retracted height L₁), independent of extendedlength (zero to L₂) are achieved by deployment of a unique verticaltelescoping structure that is horizontally movable from one connectortrack, through surrounding fibers and to another connector track underthe direction of the KBS algorithm The two-stage telescopic armarrangement is based on chosen linear lengths of a vertical rectangulartube or “C” shaped outer body, with an internal slider body maintainedin alignment by a unique sliding bearing carriage and spring preloadingarrangement within the telescopic arm. The arrangement enables aconstant length, flat, flexible electrical interface cable to be routeddynamically from the gripper mechanism to an external control system,which serves the dual purpose of pulling the internal sliding body, soit moves in synchronism with the outer body. The robotic arm and gripperconfiguration are of very narrow width, enabling it to move unencumberedthroughout the limited spaces in the fiber interconnect volume.

An automated cleaning device is further described, with the additionalfeature of integral sensing of the force on the cleaning fabric andpolished fiber optic connector ferrule during cleaning The electricalsignal produced therein is utilized to provide feedback to accuratelycontrol the robot position and maintain less than a maximum value ofcompressive force at the fiber end face. This precise control ensuresrepeatable, high quality cleaning of the fiber end face, preventing theaccumulation of particulates to thereby achieve consistently lowinsertion loss, high return loss optical connectivity, for superiorquality and consistency compared to present manual processes. In thefiber cleaning subsystem, the cleaning fabric is fed from a supply spoolthrough the cleaning cassette pad and onto a dispense spool. Thearrangement enables multiple fibers to be cleaned from a single supplyspool.

Stacked planar arrays of optical fiber take-up spools with fibersdynamically routed through a combination of eyelets, guides and rollersdistributed in a precisely spaced geometry provide a source of low lossoptical fiber connections between a fixed input array and a physicallychangeable output array. Each spool is independently tensioned to thedegree necessary to retract any excess length of fiber between theinternal one-dimensional backbone and two-dimensional output connectorarray, without subjecting the fiber to excessively sharp bends resultingfrom the controlled tension, such that the reliability and opticaltransmission characteristics of the fiber are not compromised.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts the arrangement of a number of significant functionalelements comprising a robotic fiber optic cross-connect system inaccordance with the present invention, populated with one set of eightrows and with capacity for adding more rows both below and above thoseeight rows as depicted; FIG. 1B is a block diagram of other inventivecombinations in accordance with the invention; FIG. 1C is a simplifiedperspective view illustrating the arrangement of interrelated modules,and FIG. 1D is a block diagram of some interrelated system elements inaccordance with this invention;

FIG. 2 depicts a fragmentary view of the magnetically latching internalfiber optic connector in accordance with the invention, including itsfeatures for interfacing and mating within the robotic gripper, itsrelationship to a connector row for receiving and holding the connector,and a side detailed view of the resulting magnetic repulsion forcesbetween connector rows;

FIG. 3 is an interior view of a stacked arrangement of eight connectorrows, forming a stackable module of 96 fiber optic ports with means tomagnetically engage fiber optic connectors transported thereto by thegripper, further illustrating the relationship between the connectormagnet and the connector row magnets with a tri-state configuration;

FIG. 4 illustrates an exterior view of the same stacked arrangement ofeight connector rows, producing the two-dimensional array of fiber opticports to which external cables requiring cross-connections are pluggedin;

FIG. 5 is a side view of a gripper device in accordance with theinvention, with fiber optic connector in the allocate configurationdetailing the numerous positional sensing and actuation means;

FIG. 6 is a side view of the gripper device in the unallocatedconfiguration;

FIG. 7 is a side view of the gripper device in the unplug configuration;

FIG. 8A is a partial, perspective view of a two-axis robotic actuationsystem in accordance with the invention, which moves a gripper mechanismwithin the internal fiber cross-connect volume; FIG. 8B is a schematicview of an x axis drive mechanism; FIG. 8C is a schematic view of a yaxis drive mechanism; FIG. 8D is a schematic view of the y axis drive invarious extended states; FIG. 8E illustrates the gripper z axis drivemechanism in central position, FIG. 8F in left position, FIG. 8G inright position, and FIG. 811 illustrates the velocity trajectory of thegripper stepper motor actuating the z axis drive;

FIG. 9 is a further perspective and diagrammatic view of actuationsystem of FIGS. 8A-8C, depicting the gripper at the end of a two-stagetelescopic arm in the fully extended state;

FIG. 10A is a partial view of the two-stage telescopic arm in thepartially extended state, FIG. 10B is a partial breakaway view of thevertical portion of a telescopic arm in the substantially retractedrange of travel, and FIG. 10C is a perspective view, also partiallybroken away, of different segments of the telescopic arm in thesubstantially extended range of travel;

FIGS. 11A and 11B are top perspective views of an improved fiber take-uptray for fiber tensioning and dynamic slack fiber management, eachincluding twelve individual reels and fiber guides facilitating lowloss, dynamic optical fiber routing therebetween to the centralbackbone, depicting the portion of fibers in front of the backbone inFIG. 11A and the portion of the fibers in back of the backbone in FIG.11B;

FIG. 12 is a perspective view of a portion of the stacked arrangement ofmultiple fiber take-up trays, detailing the routing of optical fibersfrom individual reels to the central backbone through low frictionO-ring shaped eyelets and soft rubber-clad rollers;

FIG. 13A is a partial cutaway perspective view of a portion of theoptical fiber reel system including sensing electronics to detect therotation of the reel during dynamic reconfiguration such that properfiber slack management can be validated, FIG. 13B is a block diagram ofa subsystem for processing the electronic signals from the sensingelectronics to establish proper system response to reel positioncommands;

FIG. 14 is a first partial cutaway perspective view detailing a part ofa gripper device and the cleaning cartridge, and in accordance with theinvention, showing a force sensor integral to a fiber end face cleaningdevice in operative position;

FIG. 15 is a second partial cutaway view of the operative side of thefiber end face cleaning device of FIG. 14 in operative position relativeto the gripper device; and

FIGS. 16A and 16B are partial cutaway bottom and top views respectively,of the fiber end face cleaning device, as depicted generally inperspective views of the system such as FIGS. 1, 9 and 10A, and showinga number of advantageous operative features therein.

DETAILED DESCRIPTION I. Robotic Cross-Connect System

This application discloses robotic cross-connect systems providing lowloss, software-defined fiber optic connections between a large number ofpairs of ports. The number of ports typically ranges from 48×48 up to1008×1008 and beyond. FIGS. 1A-1D illustrate a number of principalaspects of this system, comprised of a robot module 112 including atelescopic two axis robot arm assembly 104, a fiber optic connector endface cleaning cartridge module 105, a miniature actuated gripper orgripper assembly 103, a stacked arrangement of connector rows 102-1 . .. 102-N, and a stacked arrangement of fiber take-up reel trays 106-1 . .. 106-N. Groups of connector rows 102-1 . . . 102-8 further comprise thefront actuated patch-panel of fiber module 113. The gripper 103 is ableto unplug any fiber connector 101-n from among the array of fiberconnectors inserted along the connector rows 102, then transport it in adeterministic, optimal weaving pattern between the surrounding fiberconnectors of the array upon manipulation by the robot arm assembly 104.The process of transport thus includes a coordinated, sequential,multi-step movement of the robot and programmatic shuffling of eachconnector row 102 in accordance with the KBS algorithm as described inU.S. Pat. No. 8,463,091 referenced above. Before plugging in the fiberconnector 101-n to its chosen final port 55, the polished fiber end faceof fiber connector 101-n may be cleaned by the fiber end face cleaningcartridge module 105 as shown generally in FIGS. 1 and 9 and describedin detail below with respect to FIGS. 14 to 16B. The fiber connector101-n terminates the internal optical fiber 52, wherein this opticalfiber originates from an automatic, spring loaded take-up reel residingwithin the multiple take-up reel tray 106. The take-up reels ensure thatall internal optical fibers are maintained under slight tension in thefiber interconnect volume between the connectors 101 and the take-upreels so that they follow substantially straight-line paths for allpossible arrangements of connectors 101 within ports 55. Straight-linepaths are efficiently represented mathematically and facilitate therouting by the KBS algorithm as described in the above referencedpatents.

In reference to the block diagram in FIG. 1B and the perspective viewsin FIGS. 1C-1D, the KBS algorithm is implemented in softwareinstructions residing on server module 109 and communicating in parallelwith each Fiber Module 113-1 . . . 113-10, Docking Module 114, OpticalPower Monitor Module 115, Robot Module 112, and Power Management Module111 through the Ethernet Switch 110 and by use of the Ethernet protocolTCP/IP. In a further example, each module is powered by 24 VDC, which issupplied by a power distribution bus in the Power Management Module 111.The Robot Module 112 is in communication with a Gripper Sensor Circuit116 to detect the operative state of the fiber connector in transport,as well as a comparator circuit for a force sensor 56 (e.g. a thin filmresistive sensor) integral to the cleaning cartridge. The fiber modules113 each are in communication with a multiplexed array of reel encodersensors responsive to the rotation of any particular take up spool/reel41, the rotation resulting from internal fiber length changes due tomovement of the internal fiber connector.

FIGS. 1A, 1B, 1C further depict details of the integrated andcooperative relationship between several novel operative parts of thissystem, which further extend the art of automatic switching of selectedones of a plurality of optical fiber lines as described in theabove-referenced Telescent patents. Inputs to the system comprise aplurality of lines 62-in (FIGS. 1A and 1C) distributed in ordered spacedapart columns and rows in a coupling plane, and spaced apart by apredetermined gap, fed into one side of each individual one of an arrayof two-sided optical couplers 18. They are then connected in thecoupling plane with low loss internal fiber connectors to an opposingarray 42 of input optical couplers, and connected to a plurality oflines 62-out at the opposite side of the patch panel system 200. Theindividual rows stacked orthogonally in a first direction and areseparately incrementally shiftable laterally by one of a stack of rowshift actuators in accordance with the fundamental Knots and Braidsmethodology (referenced above). Changeable lines/optical fibers 52 (FIG.4) are coupled into the second side of the optical couplers 18 and theselines converge into a one-dimensional alignment at backbone 40 and arethen distributed into ordered levels of multiple spools serving asbuffer reels 41, as described below in more detail in relation to FIGS.11 to 13. These reels 41 compensate for path length variations asinternal fiber 52 positions and their corresponding suspended lengthsare changed, without introducing curvatures in the optical fibers thatare so sharp and noon-adiabatic that they would introduce light loss atbends. From the assembly of buffer or take-up reels 41 the fiber patternis reconfigured, typically into an array of the linearly disposedreceptacles or optical couplers 18, which can then be retransmitted orotherwise reconfigured as desired.

Given this context, some principal aspects of the present invention thatare also shown in generalized form in FIG. 1A (although shown anddiscussed in more detail below) further establish the internalcooperative relationships in form and function. For example, thearrangement of rows and columns of two-sided couplers in the connectorrow assemblies 102 provide signal interchange between lines fromopposite sides. On the internal, changeable side, the structurescomprise individual linear fixed elements of predetermined length,cross-sectional configuration and flexibility. Each of these fixedelements also supports a pattern of small permanent magnets within itsboundaries and adjacent its internal end as described in detail belowwith reference to FIGS. 2 to 4. In combination with this, eachchangeable optical fiber 52 in the system terminates in a connector rowassembly 102 of approximately matching length for coupling to anyindividual fixed element 63 with which it is to be paired. When aterminal protruding end of ferrule 10 of the optical fiber 52 isinserted in the individual optical coupler 18 of the connector rowassembly 102, an individual changeable optical circuit is completed.Together with a number of features described in detail hereafter, thatpertain either or both to design and operative relationships, thisconcept and its implementation are unique.

Interrelated functions are provided in the system that pertain to theengagement and disengagement actuation operation as well as to theinterchange of fibers to and from the couplers. Two different states oflinear engagement and a related state of disengaged physical proximityare utilized, as is described in more detail below. These states areaffected during a linear alignment phase independently of therepositioning of fibers by interweaving through the columns and rows asdescribed in detail in the previously referenced patents.

These as well as other functions are affected by commands from atrajectory control system 117 (FIG. 1B) which receives cross-connectconfiguration information from a server module 109, and a source ofupdated data, based on stored interconnection data from a memory systemin server module 109 holding updated data. Again, reference may be madeto the patents mentioned above for a full understanding of the elementsand relationships that are germane to positioning of the gripperassembly 103. These movements are substantial in orthogonal X and Ydirections and also incremental in the Z dimension under commands to theactivated gripper assembly 103 at the activator from the trajectorycontrol system 117. For these functions the system 200 deploys avertical multi-stage head positioner controlling movement in the Y axis,comprising a narrow rectangular hollow robot arm upper stage/outer stage30 inside of which a linear and narrower lower section or inner stage 35slides by spring-loaded rollers in a proportional ratio. Both receivecommand signals from the trajectory control system 117, and are drivenby a Y axis drive 33-1, typically a brushless dc servomotor or steppermotor, responsive to command signals from the server module 109. The Yaxis robot art outer and inner stages 30, 35 are moved horizontally ascommand signals are delivered from the trajectory control system 117which activates the X axis drive motor 33-2. Most of this mechanism ispositioned above the fiber interchange matrix, while the narrow fiberinterchange head acting as a gripper 103 as discussed in detail below(FIGS. 5-7) is movable vertically in the spaces between the verticalcolumn j of fibers 52 and indicated by 118-j in FIG. 3. The horizontalconnector rows 102 of the interchange matrix are selectively movedincrementally in a first horizontal direction or oppositely duringthreading through the matrix. When the activated head of the gripperassembly 103 reaches a target location in a connector row 102, it can bemoved incrementally along the Z axis to couple or decouple a targetfiber connector 101 to the selected one of the optical couplers 18.Also, along the Z axis, it can shift the target connector incrementallybetween “allocate,” (FIG. 5) “unallocate,” (FIG. 6) and “unplugged”(FIG. 7) positions. The corresponding magnet interactions between theconnector 101 magnet 13 and the row magnets 14, 15 are noted in FIG. 3.

II. Two-Dimensional Array of Switchable, Magnetically Latched,Multi-State Fiber Optic Connectors

This application further discloses a multi-dimensional array of fiberconnector devices/assemblies 101 arranged in incrementally shiftablevertically spaced connector rows 102 (FIGS. 2-4) disposed in generallyhorizontally aligned columns as best seen in FIGS. 3 and 4. Thehorizontal rows, as best seen in FIG. 2, comprise a plurality of spacedapart parallel base elements each fixed at one end to a differentoptical coupler 18 which is to receive the terminal ferrule 10 of adifferent and changeable fiber optic line 52. Thus, the array in partcomprises, as seen in the perspective views of FIGS. 1A, 3 and 4, aplurality of horizontally spaced fixed connector tracks or trackelements 39 of selected flexibility and substantial length relative totheir width and cross-sectional area. They are each fixedly attached atwhat can be called a receiver end to the transverse connector rowassembly body 102, and thus provide parallel interactive elements forreceiving the individual fiber optic connectors 101. These fixedconnector track elements 39 have a length to width ratio of greater than10:1, and are of substantially less height than width so they haveresilience in a selected range, and no or low magnetic permeability,since magnetic forces are to be used for specific deflection purposestherewith, as described below.

Each optical fiber 52 in the system terminates in an elongated connector101 leading to a ferrule 10 that engages in the optical coupler 18. Whenfully inserted, the optical fiber terminus defined by the ferrule 10 isin physical and optical contact with an external fiber terminuspre-existing in the opposite side of the two-sided optical coupler 18and in parallel adjacency to the fixed element of the connector track39. As seen in the three different and adjacent insertion positions forthe fiber ferrule 10 depicted in the partially exploded and fragmentaryperspective view of FIG. 2, a detachable portion of the connector 101extends from the ferrule 10 at the inserted end through a shaped,slightly larger housing 11 which limits the depth of insertion offerrule 10 in the optical coupler 18 and provides the means to engagewithin a matching receptacle in underside of gripper 103. The removablepart further includes an intermediate section of elongated U-shapedhousing 80 of a predetermined length that provides an external wall thatsubstantially surrounds and protects the optical fiber 52. This housingmember 80 encompasses an internal length of optical fiber that couplesat one end to the ferrule 10 and merges at the other end with anindividual different optical fiber 52 in the system. The movableconnector 101 also includes a gripper latch receiving element 12intermediately positioned along its length and a small magnet 13 of highpermanent magnetic field strength at a predetermined substantial spacingfrom its terminal ferrule 10 which provides cooperative functionsdescribed in detail below.

The connector 101 also provides predetermined optical, mechanical andmagnetic interaction with the system in general and with each differentadjacent elongated fixed connector track element 39 in particular.Since, as seen in FIG. 2, each such fixed connector track element 39extends from the underside of an optical coupler 18 in paralleladjacency to a movable fiber optic connector 101 therein, itincorporates a number of cooperative features along its length. Startingfrom the free end, the fixed element comprises a pair of bifurcated endsections serving as supportive bases for two small permanent magnets 14,of the same selected polarity, at like distances from the opticalcoupler 18 end. These may be termed the “unallocate” magnets, todesignate their operative function, while a third magnet 15 is centeredon the elongated body at a predetermined small lengthwise spacing fromthe magnet pair 14, and may be termed the “allocate” magnet. The third“unplugged” state shown in FIG. 3 is one that exhibits little magneticattraction between the inserted magnet 13 and any of the magnets 14 and15 in the fixed element. The fixed member/connector track element 39also includes a short, slightly narrowed docking section 16 intermediateits length, and an adjacent reflector surface 17 that can be used inpositioning.

The three different positions of relative engagement of the connector101 are depicted in FIGS. 2 and 3. The “allocate” state, as used hereinrefers to a relationship in which the ferrule 10 of the fiber connector101 is fully engaged within the mating sleeve of the optical coupler 18.The term “unallocate” refers to the state wherein the fiber connector ispartially engaged within the mating optical coupler 18. The “allocate”state produces near zero insertion loss and the “unallocate” stateproduces about 20 dB or more loss by virtue of the air gap between thefiber connectors. “Unplug” refers to the state in which the fiberconnector is fully withdrawn from the mating sleeve, wherein the gripperis able to withdraw a connector 101 from its corresponding connectorport 55 for movement to a different destination port 55.

In a preferred exemplification, the four magnets 13, 14, 15 are about6mm x 6 mm×3 mm in size, and their material is Neodymium 42SH. Thismagnet grade provides high magnetic attraction force of at least 500gram-force in “allocate” state, and also maintains magnetic propertieseven when exposed to high temperatures (above 150 degrees C.). The N-Smagnetization axis is typically parallel to the 6mm side. Ideally, themagnets are nickel-plated so they can be soldered to metalized pads ofthe printed circuit board connector row using a standard solder reflowprocess.

III. Parallel Rows of Fiber Optic Connectors that IndependentlyTranslate Laterally Under Software Control

A portion of the automated cross-connect structure 200 in the presentinvention thus comprises a stacked arrangement of independentlytranslatable connector rows which form a two-dimensional array of ports.A particular example with eight vertically stacked connector rows 102with a vertical spacing of about 12.5 mm is depicted in FIGS. 3 and 4.In this particular example, each row 102 is comprised of twelve parallelconnector tracks each spaced transversely by about 32 mm Each connectortrack is elongated and narrow and has selected flexure properties. TheN—S polarity and arrangement of magnets 14, 15 at the distal end of eachconnector track are identical for each track and row. As a consequence,when the rows are in horizontal (x) alignment as shown in FIG. 4, themagnets 14, 15 on each row cause the distal ends of each connector track39 to repel one another in the x and y directions. These repulsiveforces are effectively positioned to partially magnetically levitate thenarrow semi-flexible connector row assembly 102 and reduce the potentialfor interference of adjacent rows of extended connector tracks 39.

In the absence of magnetic levitation of fixed connector tracks 39detailed in FIG. 2, deflection of the extended connector track couldotherwise occur due to the tension vector of the fiber optic connector101 engaged therein. The minimization of deflection is effective toeliminate potential jamming of vertically adjacent rows and the fiberconnectors seated therein during the independent row shuffle process.

In further accordance with this invention, each connector row issupported at opposite ends by sets of three miniature rotary bearingsmounted in bearing blocks 43, 44 that provide guidance in the two axes(x, z) parallel to the surface of the connector row, and support itabove the lower row. Each bearing rides within its own track within aninjection molded plastic block on the left and right ends respectively,as viewed in FIG. 4. A central support roller 38 further provides amechanical reference point at the center of the row to preclude apotential slight bowing along its length of the mechanical row assembly102. This reference surface provides adequate support to prevent largedeflection of the connector row during gripper engagement when thegripper mechanically latches onto a particular connector track 39 (FIG.2) of the connector row.

Preferably, the connector row 102 is comprised of a printed circuitboard substrate made of common circuit board materials such as FR-4 witha thickness of 2.4 mm for high stiffness. This material is flat, stiff,inexpensive, and facilitates the reliable placement and soldering ofmagnets onto the circuit board. The ability to add circuitry alsoenables the implementation of RFID tracing of connectors as well asoptical power monitoring and detection.

Each connector row 102 is independently shiftable by a motor 20-1, onlysome representative examples of which are seen in FIG. 4 and which areshown as a unit of four motors in FIG. 4. This motor 20-1 is typically alinear permanent magnet dc stepper motor that provides precise,programmable linear translation of the row over about 37 mm range oftravel. The low friction of the bearing track blocks or assemblies 43and 44 ensures that only a minimal force (<100 gram-force) and lowcurrent are required to actuate each row.

As seen in the perspective views of FIGS. 3 and 4 of the connector rowsubassemblies 102, the narrow elongated connector elements or tracks 39in each row are positioned to define like vertical columns or stacks ofconnector elements or tracks 39. These elements are horizontallyseparated from each other by a standard distance which in this exampleis about 37 mm. For clarity only one fiber connector assembly 101 isdepicted in the upper view of FIG. 4, and shown as coupled to aninternal fiber 52 leading to an external buffer port (not shown) in thesystem. It will be understood from the referenced previously issuedpatents that interweaving through the three-dimensional mass of fibers52 is affected by laterally shifting the rows of elongated fixedelements in timed relationship to the instant vertical position of thefiber transport. The fiber is thus repositioned by being interwoventhrough the existing pattern of fibers, without entanglement, until itreaches its destination, where it is engaged in the terminal thereat, asdescribed in the earlier issued patents.

Those skilled in the art will appreciate the problems that canpotentially be encountered when navigating a thin element such as anoptical fiber through a dense population of other optical fibers. Inthis respect, the employment of static small magnetic elements on narrowelongated elements to provide strategic magnetic attraction andrepulsion forces, offers material benefits in the form of the presentlydisclosed system, both as to changing positions of elements and inmaintaining stable operating states.

IV. Narrow Form Face Gripper to Selectively Transport, Install andReposition Fiber Optic Connectors in a Dense Matrix

FIGS. 5, 6 and 7 illustrate an electronically actuable gripper device103 changeably interlocked or docking with a typical connector row 102to produce adequate local actuation force at the connector 101 to varythe engagement position of a fiber connector 101 in the two-dimensionalarray of output ports 81 as best seen together in context in FIGS. 1-4.The gripper is shown in three primary states of axial engagementcorresponding respectively to the fiber connector 101 being “allocated”(FIG. 5) (or operatively engaged), “unallocated” (or partially inserted)(FIG. 6), or “unplugged” or fully disengaged (FIG. 7) from the connectorand free to be moved elsewhere (or inserted). The gripper 103 descendsonto the connector row and stops upon optically detecting engagementwith a particular individual optical coupler 18 of the connector row 102using a reflective optical photo-interrupter sensor 27-6. The light fromthe sensor is reflected from the edge of the connector track by areflective plating/reflector surface 17 (FIG. 2), which is typicallygold, and instructs the trajectory control system 117 (FIG. 18) that thegripper is properly docked onto the optical coupler 18. The interlockingis accomplished by mechanical engagement of the gripper guides 20 withthe reduced-width docking section 16 (as best seen in FIG. 2) present oneach optical coupler 18. The gripper subsystem comprises two closelyadjacent printed circuit boards 60 and 29 lying in the narrow verticalplane which extends down to any selected row, the gripper subsystem alsoincluding multiple sensors and actuators. The upper circuit board 60 isattached to the lower end or inner stage 35 of the telescopic robotactuator (see FIG. 5). The adjacent lower sliding circuit board 29 ismounted on a linear bearing assembly, including parallel horizontalupper and lower shafts/rods 26-1 and 26-2 respectively, so that thisportion of the gripper, which is not fixed to the closely adjacentprinted circuit gripper board 60, can translate horizontally in eitherdirection between closely spaced limits within the same narrow columnarregion as the fiber connector 101. Sensors 27-1, 27-2, and 27-3 detectthe translation of the overlapping but lower circuit board 29 in theallocate, unallocated and unplug locations, respectively, as thedistance d decreases from d₁, d₂ to d₃, respectively. The lower slidingcircuit board 29 includes mechanical elements 79, 80 spaced along itslength that can retain (79) and lock (80) onto the length of the fiberconnector 101. Optical sensors are typically reflective and/ortransmissive photo-interrupters. A solenoid 23 responsive to controlsystem 117 triggers a spring-loaded mechanical latch 24 within thelocking element housing 80, wherein the state of the latch is detectedby reflective photo-interrupter sensor(s) 27-4 and 27-5 integrated onelectronic circuit board 29. In a particular example, translation of thegripper device 103 is powered by a motor 32 and timing belt driveconsisting of a timing belt pulley 28 and timing belt 25, or a highefficiency drum/wire drive system.

In a further example, to identify fibers based on their barcode and toprovide machine vision alignment, the gripper 103 may further include acamera 21 and LED illuminator 22 to capture images of the connector 101and its unique barcode identifier. Alternatively, the reel encodercircuit 51 enables any fiber to be uniquely identified by monitoring thereel encoder sensor signal 72 as the fiber is transported by thegripper.

In a particular example, the gripper 103 provides about 19 mm of lineartravel, sufficient to allocate (FIG. 5, d₁), unallocate (FIG. 6, d₂), orunplug (FIG. 7, d₃) the connector 101 as commanded where the incrementaldistances d₁, d₂ and d₃ are approximate as depicted. When unplugged, theconnector 101 can be transported vertically without interference throughthe lateral volumetric space 118-j extending from the top to bottom ofany particular column j, between and independent of all other fibers inthe matrix. When a connector assembly 101 is delivered to itsdestination connector track 39 on the connector row, its forward orferrule tip 10 is adjacent but spaced apart from the chosen fixedconnector in the assembly of connectors 102, as seen in FIG. 7. Thegripper assembly 103 is thus held in the “unplugged” position, as seenin FIG. 7 prior to allocation. In this mode the lower planar circuitboard 29 of the gripper assembly 103 is spaced apart from the connector102. The gripper guide 20 remains fixed as the lateral position of fiberconnector assembly 101 changes. Full engagement is seen in the view ofFIG. 5, in which the lower printed circuit board 29 has been shifted tothe left by the actuated gripper assembly 103 in response to energizingthe motor 32 of gripper actuator. This is the “allocate” position, incontrast to FIG. 6, which shows the “unallocate” or partially engagedposition, and FIG. 7, in which there is no connector engagement.

V. Telescopic Robotic Vertical Actuator

The gripper device 103 is mounted on the lower end of, and istransported by, a two-axis robot mechanism 104 as illustrated in FIGS.1A, 8A, 9, 10A, 10B and 10C. The robot device 104 is telescopic in thevertical direction to enable the gripper device 103 to reach a largenumber of cross-connects within a height constrained installation. Itcomprises a rectangular outer arm or outer stage 30 and an inner arm orinner stage 35, and is movable in the horizontal direction by a drivebelt 25 or wire/string extending between fixed end points. The verticaltelescoping and horizontal movement capability ensure that the arm canreach all connectors within the two-dimensional array of rows ofconnector ports 55 (FIG. 2) without adding excessive height to theoverall robotic cross-connect system above the 2.15 meter heightstandard preferred by the industry.

Telescopic robot arms in the prior art do not have the requiredstiffness nor the aspect ratio/miniaturization needed to descend andoperate in between the internal fiber connectors with requisitepositioning accuracy (˜+/−3 mm) of the internal connector with tensionedfiber attached. In the present system, however, a vertical linear outerstage 30 of a slender hollow rectangular or partial rectangular crosssection receives a sliding interior member or inner stage 35 of smallercross section. As seen in FIG. 10B the top end of the arm or inner stage35 of the robot arm includes an internal carriage that spring-loadsroller bearings 92, 93, which contact the inner side walls of therectangular or “C” shaped hollow cross section outer arm or outer stage30. In the preferred embodiment the outer stage 30 and inner stage 35are stainless steel or plain steel; however, aluminum, plastic,fiberglass and carbon fiber are all suitable alternatives.

The gripper mechanism 103 is attached to the lower end of the innerstage 35 of the robotic arm system, which telescopes within the tubularouter stage 30 and variably extends in length, as seen in FIGS. 9 and10A. The electrical cable 37 carrying electrical signals for the sensorsand actuators embedded within the gripper 103 travels up the inner stage35, then through the outer stage 30, exits the top of the outer stage30, wraps around an upper pulley 31 and then extends down to a fixedattachment at point 36. As seen in FIGS. 8A and 9, a Y axis motor 33-1,for example a dc servomotor or stepper motor, drives the tubular outerstage 30 up and down through a timing belt drive mechanism attached tothe top and bottom of the outer stage 30. The multi-conductor electricalribbon cable 37 is rigidly affixed to the top of the inner stage 35 andits midpoint is fixed at a cable attachment point 36. As the outer stage30 moves up and down (FIG. 8D), the inner stage 35 moves at twice theouter stage distance because of the action of the cable 37 looping overthe pulley which is attached to and moves with the outer stage.

The telescopic arm exhibits relatively low transverse compliance orequivalently high rigidity. In a particular example, less than 2 mm ofdeflection results for about 50 gm of transverse force appliedperpendicular to the telescopic direction (i.e. in x and z directionsdefined in FIG. 1) and high length efficiency (ratio of the telescopicarm range L₂=1.5 meters to arm retracted height L₁=1 m, FIGS. 9, 10A,10B). This rigidity is important to prevent the tension from the fiber52 attached to connector 101 from dragging or deflecting the telescopicarm out of true vertical alignment. In contrast to prior art telescopicarms (e.g. drawer slides, telescopic booms, etc.), the transversecompliance is independent of extended length L₂′ (0 to 1.5 meters) ofthe telescopic structure. This is a significant advantage of the presentinvention, because reliable engagement of any connector 101 across theextended front connector array, by gripper 103, also requires somenon-zero level of deflection and consistent deflection and compliancecharacteristics to enable automatic, passive alignment via themechanical capture method. On the other hand, low vibration at alllocations of the connector array at the end of the telescopic arm shouldalso be maintained.

In accordance with the invention, tightly controlled compliancecharacteristics are achieved by (1) providing a roller bearing systemfor the outer, first stage that is very stiff and (2) providing a rollerbearing carriage for the inner, second stage, wherein a set of bearingsare located at the upper 150 mm of the inner, second stage, suitablypreloaded by mounting the inner carriage on spring loaded roller bearingflexures 76-1, 76-2 so that the carriage is guided within the tube(outer stage) 30 with high angular consistency. The bearing system isillustrated in part in FIGS. 10B and 10C and is comprised of internal xaxis support bearings 92, and internal z axis support bearings 93. Topreload the system there are further preloaded internal x supportbearings 92′ at opposite, suspended ends of flexure 64 and preloadedinternal z support bearings 93′ at opposite, suspended ends of flexure76.

The bearing flexures 76-1, 76-2 are, for example, semi-hardstainless-steel sheet metal structures deflecting under load like a leafspring, with radial ball bearings 93 attached at both ends of theflexure arm. Mechanical stress arising from deflection is by designsmaller than the yield stress of the material, thereby preventing theflexure from permanently deforming. These flexure arms 76-1, 76-2 areaffixed to the rigid, steel inner second stage at the top of the innerstage 35 so that the opposite bearings are preloaded and in contact withthe outer tube as they ride up and down the inner cavity of this outerfirst stage 30. The friction of the bearing assembly is sufficiently lowthat the inner stage descends controllably within the outer tube due togravity alone and is supported by the electrical ribbon cable 37. Thiscable serves two purposes: it resists gravity preventing the arm fromdropping and transmits signals from the gripper 103 to the trajectorycontrol system 117. This cable 37 is routed around the pulley 31attached to the top of the outer stage 30 and affixed to the main robotx axis carriage 61.

FIG. 8B is a schematic top-view of the horizontal or x-axis carriagedrive system, consisting of a timing belt 25-1 with drive pulley 28-2coupled to the X axis servomotor 33-2 with gearbox at one end, and anidler pulley 28-1 at the opposite end. The x-axis carriage of platform61 is attached to timing belt 25-1, which translates the platform fromone end of the x rail to the other end.

FIG. 8C is a schematic side-view of the y-axis actuation system,detailing the timing belt pulley drive system. A first timing belt 25-2is affixed at opposite ends to the outer y axis tube or outer stage 30and is used to drive the tube robot arm/outer stage 30 up and down.Timing belt 25-2 is redirected and wrapped around timing belt drivepulley 28-6 by a pair of idler rollers 28-7 and 28-4. Drive pulley 28-6and reduction pulley 28-5 are rigidly attached to a common centralshaft. The drive motor 33-1 turns a small drive pulley 28-3. A timingbelt 25-3 wraps tightly around both the small diameter pulley 28-3 and aspaced apart large diameter pulley 28-5. The ratio of large to smallpulley diameters is typically 5 to 10 to produce a torque multiplier.

As depicted in FIG. 8D, driving the outer arm or outer stage 30 with thetiming belt raises or lowers the pulley 31 by a corresponding distanceX, since the pulley 31 is mounted to arm or outer stage 30. The pulley31 is free to spin. A fixed length elongated band, cord, wire, or cable37 is attached at one end to a fixed point 36 of the y-drive platform,and the opposite end is attached to topmost portion of inner stage 35.This configuration results in the robot arm inner stage 35 moving at 2X,twice the distance of the robot arm upper or outer stage 30. FIG. 8Dillustrates the configuration of the arm at various degrees oftelescopic extension. The wire or cable 37 is wrapped around movingpulley 31. For a particular distance X₁ the outer stage arm 30 moves,the pulley also moves in the same direction the same distance X₁. Sincethe cable is a fixed length and suspends the inner stage 35, as thepulley moves a distance X₁ the translating end of the cable moves by adistance 2X₁. As a result, the inner stage 35 moves a distance 2X₁.

A particular exemplification of the gripper shown in FIGS. 8E, 8F and8G, to which reference is now made, details a drive mechanism forreliably incrementing a selected optical fiber mounted on the fixedprinted circuit board 60. The gripper includes a gripper activator inthe form of a stepper motor 32 which rotates a gripper drive drum 122 onwhich a cable/wire or timing belt 25′ is wrapped with a controlledlooseness or “play.” The winding of wire 25′ on drum 122 pulls the outerprinted circuit board structure 29, riding on parallel rods 26-1, 26-2to the right (as shown by the arrow in FIG. 8F) by tightening theportion of wire 25″, seen here on the left side of FIG. 8F, or left(FIG. 8G) by tightening the portion of wire 25″ as seen on the rightside of FIG. 8G. The provision of a chosen degree of slack within thewire provides a significant improvement in the amount of torque andcorresponding linear actuation force available from a given steppermotor. Under typical operating conditions, the motor 33 must drive thegripper from an initial position of maximum resistance, therebyrequiring the maximum torque at the start of motion. If the wire has noslack, the motor would need to overcome a large initial force as itaccelerates. This is the force to plug-in or un-plug an internal LCconnector 101. It is known in the art that stepper motors stall underconditions of high torque during an initial start-up acceleration. Byproviding a length of slack wire 25′ on each side of the drum 122, themotor initially experiences only minimal load as it takes up slack bywinding excess wire on drum 122. As a result, the motor is not subjectedto the large load until after (1) it reaches a minimum velocity/is nolonger in acceleration phase and (2) the wire no longer exhibits slackin taut section of wire 25″ on one side or the other (e.g. FIGS. 8F,8G).

The stepper motor pull-in torque is the measure of the torque at whichthe stepper motor will stall when it is starting from rest. The pull-incurve defines an area called the start/stop region. When operating withproper selection of parameters such as velocity, acceleration and loadtorque, the motor can be started instantaneously with a load applied andwithout loss of synchronism. The slack wire in the cable drive ensuresthat this load torque is initially low (FIG. 811). In contrast, steppermotor pull-out torque is the torque that can be produced at a givenvelocity until the motor stalls. The pull-out torque is typically atleast a factor of 2 higher than the pull-in torque. It is thereforeadvantageous for the gripper stepper motor to operate in the pull-outtorque regime when experiencing the largest loads associated withplugging-in/unplugging internal optical connectors 101, to ensure themaximum torque output for a given z drive system.

VI. Slack-Fiber Take-Up Reels and Rotation Sensing

The fiber connectors in the connector assembly 101 terminate as outputfibers 52 (FIG. 11A) from low profile spring-loaded reels 41 (FIG. 11B)that are arrayed on a planar, low profile tray 47, as shown in FIGS. 11Ato 13A. This example of a fiber tray assembly 106 (FIGS. 11A and 11B)includes twelve fibers that are rendered individually and independentlyself-tensioning, by reels 41 to which the fibers 52 are guided afterpassing through a center backbone 40 of linearly arrayed flexibleguides. Flexible guides are typically a low friction tubing materialsuch as PTFE, FPA, FEP, etc. In the particular example shown here, theopposite ends of each of the twelve fibers exiting the backbone haveoriginated in connectors that are plugged individually into differentones of a linear array of mating sleeves or optical couplers 18. Theinternal paths of the fibers 52 between the interior reels 41 and theoutput connector array 42 are depicted in FIG. 11B.

The fragmentary perspective view of FIG. 12 details the paths of thefibers to individual reels including front, dynamically moving fibers 52exiting from the reel fiber exit location 50 and terminated inconnectors to form the dynamic output connector array 81 (FIG. 1A), andrear, fixed-length fibers 54 (FIG. 11B), also exiting from reel fiberexit location 50 and ultimately terminated in connectors to form thestatic input connector array 82. As seen in FIG. 12, the fibers arerouted through O-ring eyelets 49 and around fiber rollers 48 to redirectthe dynamically moving fibers with low friction and low stress as theyexperience an angular change of about 90 degrees while passing around anintervening reel 41. As the fibers 52 are withdrawn or retracted backinto a reel, the reel 41 rotates, causing the reel's internal fiber tospiral on its underside (as disclosed in U.S. Pat. No. 8,068,715) so asto coil or uncoil, respectively. As seen in FIG. 13A, the outer wall ofthe reel is segmented and/or colored with alternatingreflective/non-reflective circumferential segments 46 such that areflective photo-interrupter 45, in combination with an electronicmultiplexing and counter circuit 51 detects the number of turns the reelundergoes. This provides validation during operation that the properlength of output fiber 52 is present on the reel as a function of themovement of fiber connector assembly 101 during robot control.

Different novel aspects of an improved multi-reel module are alsodepicted in FIGS. 11 to 13. FIGS. 11A and 11B, for example, illustratean advantageous geometric layout of twelve take-up reels 41 forproviding individually adjustable lengths of optical fiber. Here, eachfiber tray assembly 106 distributes individual optical fibers from thebackbone 40 to reels 41 which are linearly aligned in spaced apart setsof four extending from front to back on the reel tray 47. Furthermore,these reel sets are each adjacently positioned so that the pairs ofadjacent reels each define an acute angle relative to the front to backaxis on the tray 47. There are thus six reels on one side of the tray47, and six reels on the opposite side positioned in oppositely angledpairs with an open central area of the tray 47 providing a pathway toinput fibers from the backbone 40 input.

The fiber 52 inputs to the different reels 41 feed into the central areaand are directed clockwise about the individual reels in the left (asseen in FIG. 11B) side set of six reels, and counterclockwise about eachof the six reels on the right-side set. Since the reels of each pair areclosely adjacent but spaced apart, the paths of fibers incoming from thecentral backbone 40 are different, dependent on whether a reel is theinnermost one of the angled pair, or the outermost one of the pair. Theproblem is resolved, while still maintaining compactness and control, bythe fiber guide geometry shown in FIG. 12, to which reference is nowmade. The inner (closest to the center) reel 41 of an angled pairreceives a variable length of fiber 52 to take up or supply fiber asneeded during reconfiguration. The variable length reconfigurable,auto-tensioned fiber 52 is controllably guided with curvature of greaterthan a minimum acceptable bend radius (typically >5 mm) The reels ofeach pair are closely adjacent but operatively distinct, which result ismade possible by the angled and spaced geometry of the reels 41 of anymodule. At the opposite end of the fiber, a fixed rear length of fiber54 is fed to the individually coupled lines in the array 42 (FIG. 11B).

A useful novel expedient for monitoring the dynamic operation of themultiple reels 41 is provided by the sensor arrangement depicted in FIG.13A and an example of the associated multiplexing circuitry as depictedin FIG. 13B. Referring to those FIGS. it can be seen that a smallreflective photo sensor 45 is mounted in a thin wall adjacent theperiphery of a take-up reel 41. The sensor 45 is positioned outside thetake-up reel and generates a signal which varies with the then adjacentcircumferential segment 46 of the take-up reel 41. There are, as seen inFIG. 12, seven such indented (small radius) segments, evenly distributedaround the periphery of each fiber take-up reel 41. Thus, as the reelrotates to feed out or take up fiber, a responsive signal from theassociated sensor 45 is sent to reel encoder circuits 51. These circuits51, one for each individual reel 41, provide signals responsive to thechanging rotational position of the reel. To read out any particularsensor, the electronic multiplexers 70, 71 in the internal monitoringsystem (FIG. 13B) must be set to its particular address. As shown inFIG. 13B, multiple individual power and ground lines from differentsensors 45 can be shared by feeding into separate multiplexer circuits70, 71 to selectively activate a particular reel and generate signals 72corresponding to its particular reel 41, for processing by commandcircuits which monitor the operation of the multiple reels.

VII. Automatic Fiber Endface Dry Cleaning Cartridge with IntegralSensing for Process Control

Reference is now made to FIGS. 14, 15, 16A and 16B, which illustratepartial cutaway and perspective views of an advantageous cleaner device105 detailing how force sensing is effected by means comprising acompliant pad 57 behind a cleaning fabric 58, further including a forcesensor 56 within the compliant pad 57 which detects the existing ferruletip compressive force F, the direction of which is indicated by theblock arrow in FIGS. 14 and 15. A fiber connector 101 within the gripper103 is raised to above the fiber interconnect volume and the top mostfiber module 113-10 along the y axis so that the connector is at theelevation of the cleaning cartridge 105. The cleaning cartridge ismounted rigidly to the bottom of the translating x axis carriage 61 andmoves with the carriage as it translates in x. The cleaning fabric isadvanced by moving the robot to the far right, to depress the cleaningcartridge advance lever 75 which advances the cleaning fabric to aclean, unused portion of the fabric. In a particular example, the forcesensor 56 is a substantially planar element on a flexible substrate withinternal electrode features that include two wire terminals 59, andproduces a resistance change proportional to the average local forcewithin the sensing region. The sensing region is typically 5 to 10 mm indiameter and the thickness of the sensor is typically 0.25 to 0.5 mm Thesensor wires 59 are interfaced to external electronic circuits 107including a voltage divider, wherein the target force sensing thresholdis 100 gm-F and the reference resistor value of the voltage divider isselected to produce a voltage of about 2.5V for a supply voltage of 5V.A typical resistance crossing value for the force sensor is 100KΩ. andthe reference resistor is typically chosen to be 1MΩ. A comparator inthe circuit 107 converts the analog voltage on the voltage divider intoa digital signal. This digital signal is input to a controller 108 andmonitored by embedded control software to accurately terminate thegripper 103 and fiber connector 101 advancement at the prescribedcleaning fabric compression force. The robot gripper 103 (FIG. 14) movesthe fiber end face/ferrule 10 of the connector 101 until the fiber endface touches the fabric and compresses the compliant pad 57 behind thefabric. The force sensor is integral to the compliant pad 57 and sensesthe compression therein. The desired force for automated cleaning is inthe range of 25 gm-F to 250 gm-F. Control of force within a range isimportant because excessive force can create tears in the fabric andcontaminate fiber; inadequate force can result in incomplete cleaning

Furthermore, in accordance with the invention, the cleaning cartridge105 which is disclosed provides integral sensing of the cleaning fabricconsumption. Referring to FIGS. 16A and 16B, the cleaning cartridgeincludes sensing means, such as a reflective photo-interrupter 77, todetect the advance of the cleaning fabric 58 from its spool, feeding itssignals to the electronic circuits 107 and 108 (FIG. 14). The cleaningcassette fabric 58 is fed from the supply spool 73 past the cleaningcassette pad 57 and the sensor 56 to the dispense spool 74. The cleaneradvance lever 75 is actuated to feed the fabric 58 in increments asneeded by horizontal movement along the x axis to depress the lever whenit strikes the hard stop in the vicinity of the rightmost limit oftravel. As is evident from the perspective view in FIGS. 14 and 15 ofthe relationship of the gripper assembly 103 when it is in operativerelationship to the cleaning cartridge 105, the supply spool 73 anddispense spool 74 straddle the cleaning cassette pad 57. The spacingbetween the two spools thus facilitates accessing any chosen opticalfiber ferrule 10 in operative position for cleaning and return tooperative position in the precisely ordered bank of changeable opticalfibers. At the same time, the source of cleaning material is largeenough for many different cleaning sequences, but readily replaced whenadequately used or when an inspection is needed.

In conclusion, new mechanisms and designs to achieve reliable operationof compact, robotically reconfigured, software-defined fiber opticpatch-panels are disclosed herein. Those skilled in the art will readilyobserve that numerous modifications and alterations of the devices maybe made while retaining the teachings of the invention.

APPENDIX—DRAWING LEGEND

10 Polished fiber ferrule

11 Plastic connector housing

12 Gripper mechanical locking feature

13 Connector magnet

14 Connector row unallocated magnets

15 Connector row allocate magnet

16 Reduced width mechanical feature for docking

17 Edge plated reflector

18 Fiber optic union adapter

19 Connector row actuator

20 Gripper guides

21 Camera

22 LED illuminator

23 Solenoid

24 Latch of solenoid

25 Cable or timing belt

25′ Loose cable drive

25″ Taut cable drive

26 Gripper translation shaft

27 Reflective photo-interrupter

28 Timing belt pulley

29 Gripper sliding printed circuit board

30 Robot arm outer stage

31 Telescopic arm cable pulley

32 Gripper actuator

33 Motor

35 Robot arm inner stage

36 Fixed cable attachment point

37 Electrical cable

38 Central support roller for row

39 Connector track

40 Backbone with flexible guides

41 Fiber take-up reels

42 Rear fiber optic union adapters

43 Left bearing block

44 Right bearing block

45 Reflective photo sensor

46 Reflective reel segments

47 Tray for reels

48 Fiber rollers

49 Ring eyelets

50 Reel fiber exit location

51 Reel encoder PCB

52 Internal, reconfigurable, auto-tensioned fibers

53 Reel axis of rotation

54 Rear, fixed fibers

55 Reconfigurable fiber optic connector ports

56 Cleaning cassette sensor

57 Cleaning cassette pad

58 Cleaning cassette fabric

59 Pair of electrical wires from force sensor

60 Gripper center printed circuit board

61 Robot x carriage

62 External fibers

63 Output fiber connector mount

64 Magnetic steel insert

70 Column electronic multiplexer for sensor

71 Row electronic multiplexer for sensor

72 Reel encoder sensor signal

73 Cleaning fabric supply spool

74 Cleaning fabric dispense spool

75 Cleaner advance lever

76 Spring loaded rollers

77 Cleaning fabric usage sensor

78 Output connector array support structure

79 Gripper connector retaining feature

80 Gripper connector locking feature

81 Dynamic two-dimensional array of output ports

82 Static two-dimensional array of input ports

101 Fiber connector assembly

102 Connector row assembly

103 Actuated gripper assembly

104 Two axis robot

105 Cleaning cartridge

106 Fiber tray assembly

107 Voltage divider, mux & comparator circuit

108 Controller & logic

109 Server module

110 Ethernet switch module

111 Power management module

112 Robot module

113 Fiber module

114 Docking module

115 Optical power monitor module

116 Gripper sensor circuit

117 Trajectory control system

118 Gripper travel location within column gaps

119 Projection of fiber trajectories onto xz plane

120 X axis drive

121 Y axis drive

122 Gripper drum

200 Automated patch panel system

1. (canceled)
 2. An apparatus comprising: a plurality of connector trackelements, each extending from a coupling plane, wherein a particularconnector track element of said plurality of connector track elementsincludes a distribution of at least two magnets adjacent an end thereof,a polarity of the magnets on said particular connector track elementbeing selected to provide magnetic repulsion as to at least one adjacentconnector track element of said plurality of connector track elements.3. The apparatus of claim 2, wherein the plurality of connector trackelements each extend substantially perpendicularly from the couplingplane.
 4. The apparatus of claim 2, wherein the polarity of the magnetson said particular connector track element is selected to providemagnetic repulsion as to at least one vertically adjacent connectortrack element.
 5. The apparatus of claim 2, wherein the connector trackelements have a length to width ratio of greater than 10:1.
 6. Theapparatus of claim 2, wherein the coupling plane comprises a number ofoptical couplers disposed in parallel rows, and wherein said connectortrack elements are each attached adjacent a different optical coupler.7. The apparatus of claim 2, wherein the connector track elements arespaced apart by a first predetermined gap in a first direction, andwherein the first predetermined gap is sufficient to allow non-contactpassage of a telescoping drive.
 8. The apparatus of claim 2, wherein thedistribution of at least two magnets is adjacent an unattached end ofsaid particular connector track element.
 9. The apparatus of claim 2,wherein said plurality of connector track elements are arranged inparallel rows in said coupling plane, spaced apart in the rows by apredetermined gap in a first direction, the rows being stackedorthogonally to the first direction to form columnar gaps.
 10. Theapparatus of claim 9, wherein the columnar gaps are of sufficient widthto allow non-contact passage of a telescoping drive.
 11. The apparatusof claim 10, wherein the telescoping drive comprises an actuatablegripper at an end thereof, and wherein the telescoping drive isconstructed and adapted to transport said gripper between connectortrack elements.
 12. The apparatus of claim 11, wherein the gripper isconstructed and adapted to grab and transport a fiber optic connectorbetween connector track elements.
 13. The apparatus of claim 12, whereinthe gripper moves a fiber optic connector between connector trackelements without entangling surrounding optical fibers.
 14. Theapparatus of claim 11, wherein a multiplicity of optical fiberconnectors are each connected with corresponding ones of said pluralityof connector track elements, and wherein the gripper is constructed andadapted to engage and disengage any of the multiplicity of optical fiberconnectors with or from a corresponding connector track element.
 15. Theapparatus of claim 14, wherein a particular optical fiber connectorcomprises a connector magnet, and wherein engaging said particularoptical fiber connector with a particular track element uses saidconnector magnet and at least a first magnet of said at least twomagnets of said particular track element.
 16. The apparatus of claim 2,wherein said at least two magnets of said particular connector trackelement includes a first magnet positioned to interact with one or moremagnets on a connector assembly.
 17. The apparatus of claim 2, whereinsaid at least two magnets of said particular connector track elementincludes at least three magnets, two of said magnets spaced apartlaterally on a terminal segment of the connector track element and athird of said magnets being longitudinally closer to the opposite end ofthe connector track element.
 18. The apparatus of claim 17, wherein thethird of said magnets defines a longitudinal engagement limit of anoptical fiber connector assembly engaged with said particular connectortrack element.
 19. A connector track element comprising: a distributionof at least two magnets adjacent a first end thereof, a polarity of themagnets being selected to provide magnetic repulsion as to at least oneadjacent connector track element, wherein said connector track elementis attachable at a second end thereof to a coupling plane.
 20. Theconnector track element of claim 19, wherein said at least two magnetsincludes at least three magnets, two of said magnets spaced apartlaterally on a terminal segment of the connector track element and athird of said magnets being longitudinally closer to the opposite end ofthe connector track element.
 21. The connector track element of claim20, wherein the third of said magnets defines a longitudinal engagementlimit of an optical fiber connector assembly engaged with said connectortrack element.
 22. The connector track element of claim 19, wherein theconnector track element has a length to width ratio of greater than10:1.